This invention relates to image processing systems. More particularly, the invention relates to systems that process images using a layered coding technique in which different tracks on a storage medium store different layers of data that can render either a standard definition or high resolution image while storing the data efficiently.
Although a new high-definition television (HDTV) standard is emerging, most existing televisions and television receivers are low-resolution (i.e., standard definition televisionsxe2x88x92SDTVs). Typically, the maximum resolution supported by a standard definition television is a horizontal resolution equivalent to 720 vertical lines by 480 interlaced horizontal scan lines with an effective resolution of approximately 350 lines of vertical resolution. The Advanced Television Systems Committee (ATSC) HDTV broadcast standard supports resolutions including 1280xc3x97720 lines per picture, which is approximately four times the number of pixels that can be resolved in a standard definition picture.
DVDs (Digital Video Discs or Digital Versatile Discs) are a popular medium for distributing video and audio/video programs, such as movies, musical concerts, and other video programs. The current DVD standard provides a maximum resolution of 720xc3x97480 for programs recorded on a DVD. Thus, the current DVD standard does not take advantage of the higher resolutions supported by HDTVs. Most DVDs are encoded from movie film or other storage media that supports the higher resolution of HDTVs. Therefore, the higher resolution version of the video program is typically available when the DVD is created, but the resolution is reduced to 720xc3x97480 (standard definition) when the DVD is manufactured.
As more HDTVs are manufactured and sold, more end users will desire DVDs having a higher resolution that matches the capability of their HDTV. However, to avoid obsoleting the large number of existing standard definition televisions and disc players, high-resolution DVD devices (e.g., high-resolution DVD players) will also need to support DVD programs recorded in the prior standard definition format.
One solution to this problem creates two different DVDs for each video program (e.g., one DVD that is encoded for standard definition devices and a different DVD encoded for high-resolution devices). This solution is undesirable because it requires the creation, distribution, and stocking of two different DVDs. Furthermore, until a large number of high-resolution DVD devices are sold in the marketplace, the cost of creating a small number of high-resolution DVDs may be too high.
Further, it would be undesirable to store two complete versions of a DVD title on the same disc (i.e., both a standard definition version and a high definition version). A high definition version would require the fall capacity of both physical layers of one side of a DVD, thus requiring an expensive dual-sided, dual-layer disc to also store the standard definition version of the title on the other side of the DVD. This is an inefficient and expensive solution because the standard definition data is stored twice on the same disc in two forms.
Therefore, a system is needed that allows both a standard definition version of a video program and a high-resolution version of the same program to be efficiently stored on a single DVD in a manner that allows the standard definition version to be compatible with existing equipment.
Layered coding, which separates a high-resolution image into a base layer and an enhancement layer, is described. A storage medium, such as a DVD, has at least two different data storage tracks (also referred to as data streams). One data storage track is used to store the base layer and the second data storage track stores the enhancement layer. A standard definition image is generated by decoding the base layer data. A high-resolution image is generated by decoding and combining both the base layer data and the enhancement layer data.
In one embodiment, an encoding system encodes a base layer representing a standard definition portion of a source image and encodes an enhancement layer representing a high-resolution portion of the source image. The base layer is stored on a first data storage track of a storage medium and the enhancement layer is stored on a second data storage track of the storage medium.
In another embodiment, the first data storage track is a default camera angle track and the second data storage track is a second camera angle track.
In a particular implementation of the system, the storage medium is a DVD.
Another embodiment provides a decoding system that decodes a base layer from a first data storage track of a storage medium and decodes an enhancement layer from a second data storage track of the storage medium.
In a described implementation, the base layer and the enhancement layer are decoded simultaneously.
A particular embodiment decodes the base layer from a default camera angle track and decodes the enhancement layer from a second camera angle track.